Five Whole-Body Benefits of Probiotics

Did you know 61% of Americans suffer from digestive discomfort1? For many, probiotics offer a potential solution to this chronic problem. Specific strains of probiotics have been shown to support ease of bloating and promote healthy regularity. But the benefits of probiotics go far beyond the gut. Certain probiotic strains can impact your systemic health — think improvements in everything from the health of your skin to heart function. But choosing the right probiotic is vital — and to do that, we need to understand not only how probiotics work, but their impact on whole-body health. Read on to learn more.

Five Whole-Body Benefits of Probiotics

1. Probiotics and Digestion

In search of a way to support your gut health? A daily probiotic may help. Often the most immediate effects of starting a probiotic are recognizable improvements to digestion. In addition to supporting ease of bloating and expulsion, certain probiotic strains can trigger neurotransmitters that stimulate muscle contractions for increased motility — think smooth, regular stools. For instance, in a 300-person study, researchers discovered certain strains supported gastrointestinal functions: bowel movement regularity, stool consistency, ease of expulsion, bowel movement comfort, and ease of occasional bloating.²

2. Probiotics and Gut Barrier Integrity

The human intestinal lining is formed by a single layer of epithelial (or “surface”) cells and a thick layer of mucus. This is what we call your gut barrier. It has two vital jobs: absorbing beneficial nutrients and providing protection against harmful substances.

With over 100 times the surface area of your skin, your gut is the largest exposed external surface on your body. On a daily basis, it interacts with the food you eat, the molecules you breathe, and at times, potential toxins that might attempt to invade your body. Because of this, your gut faces many perturbations (think: NSAIDs such as aspirin and ibuprofen, overuse of antibiotics, alcohol, and even high-intensity exercise). If your intestinal lining is weakened, substances that don’t belong in your body can enter the bloodstream, triggering autoimmune responses such as inflammation, allergies, irritable bowels, migraines, pain, fatigue, and more.

So, what do probiotics have to do with this? Well, certain strains have been shown to influence mucus composition and enhance the gene expressions involved in tight junction signaling — in other words, promote the integrity and “tightness” of your gut barrier, effectively keeping the good in and sealing the bad out.³

3. Probiotics and Skin Health

While the skin microbiome isn’t as vast as the gut microbiome, its 100 billion microorganisms play a vital role in our body’s outermost defense system, from identifying unknown organisms to managing inflammation. The skin microbiome also helps determine skin texture and appearance. For instance, an overabundance of one kind bacteria can lead to oily skin; a deficiency in another may cause dryness or itchiness.

In a 2016 study, scientists identified two of the root causes of adult acne — an imbalance in the gut-skin axis, and irregular insulin production. When oral probiotics were administered, participants exhibited a 32% reduction in acne symptoms compared to the control group.Another 2016 study looked at the link between a bacterial imbalance and rosacea, and found that 64.5% of patients who underwent oral probiotic treatment were still in remission 3 years later. A consumer warning, however: while “probiotic” eye creams and skin serums may sound promising, these topical formulations aren’t proven to have the same effects as ingesting the specific probiotic strains highlighted in these studies (that’s because there’s little regulation in the probiotic market — more on that later!).

4. Probiotics and Mental Health

Have you heard of the gut-brain axis? The human gut also plays home to over 100 million nerve cells, part of a complex system called the enteric nervous system (ENS). These neural circuits control the gastrointestinal system from your mouth to your intestines, and by emitting hormones into the bloodstream, they provide constant feedback to your brain. This is the reason you know you’re hungry, or if your last meal made you feel overly full — and it’s this network that researchers are investigating for the potential benefits of probiotics on mental health.

While it’s certainly too early to say that any one probiotic could “cure” a serious mental health disorder, researchers are working to uncover links between microbes and conditions such as anxiety and depression. For example, a 2019 review of 21 studies on probiotics and anxiety revealed that modulations of the intestinal microbiome through probiotic therapy and diet changes reduced anxiety symptoms in over half the patients, suggesting the potential for treating mental health from the gut up.

5. Probiotics and Vitamin Synthesis

While they are often found in the same aisle at the pharmacy, probiotics aren’t vitamins. However, certain probiotics can create them. You’ve likely heard about folate, an essential B vitamin that is not only important for fertility and pregnancy, but also responsible for DNA and red blood cell production, helping prevent anemia and contributing to cellular health. Certain probiotics contain a strain that can actually synthesize folate from within the body, providing an endogenous source of folate locally in the gut.

Let’s back up for a minute — before we talk about how to find a probiotic that can support the benefits above, we have to first answer this question: What are probiotics?

According to a 2002 United Nations / WHO Expert Panel chaired by scientist and researcher Dr. Gregor Reid (who just happens to be Seed’s Chief Scientist), the globally-accepted, scientific definition of a probiotic is: Live microorganisms which, when administered in adequate amounts, confer a health benefit on the host.

Let’s break that down:

Live microorganisms: This means exactly what it sounds like — the beneficial microbes must be “alive” upon consumption. In science, we refer to this as “viability.” We take this one step further and ensure our probiotic organisms survive the stages of digestion, and make it alive, to the colon.

Adequate amounts: The number of the microbes in a probiotic dose will be listed on the label, measured in either CFU (Colony Forming Units) or, our preferred method, AFU (Active Fluorescent Units). This amount should match the dosage used in the corresponding clinical trial demonstrating the benefit of the particular bacterial strain.

Health benefit: Why would you take something that hasn’t been studied to be effective? Each specific strain of bacteria (not just the species — more on this later) must have been shown through scientific research to be beneficial.

Host: That’s you! (Or your mom, or a dog, or a colony of honey bees, or for whom the probiotic is intended.)

With this in mind, it’s important to understand that there’s no such thing as a “best” probiotic. Why? Well, your physiology and experiences are unique — as are your particular needs. That’s why it’s more important to focus on strain specificity, and to look for probiotics that have been shown to provide your desired outcomes.

However, there is such a thing as a “scientifically validated” probiotic. As gut mania takes over the shelves of pharmacies and grocery stores, it’s important to discern between products that meet the scientific definition of a probiotic, versus those that are just co-opting the term (like those eye creams we mentioned above).

The next time you’re navigating a crowded probiotics aisle, here are three key questions to consider:

Which strains — not just species — are included in this probiotic?

Within each species of bacteria, there can be hundreds or thousands of strains — and each strain differs as much from each other as a golden retriever does from a french bulldog. When you’re looking for a probiotic, you’ll want to examine the specific strains it contains (it’s the long, difficult-to-pronounce name followed by a set of numbers or letters). Here’s an example:

  • Escherichia coli O157:NH is a strain of E. coli famously known for causing hemorrhagic diarrhea and mass lettuce recalls. However, a different strain, E. coli Nissle 1917 was actually one of the earliest probiotics ever developed, during World War I, and has been studied as a treatment for ulcerative colitis and irritable bowel syndrome.

Are the strains in this probiotic included in clinically studied dosages?

You’ll likely see something called CFU (Colony Forming Units) on a probiotic label. The CFU indicates the amount per dose, and will usually be enormous (in the billions). While it’s common to think “bigger = better,” what’s actually important is whether that dose matches the dose used in clinical trials or scientific studies.

Which brings us to our next point …

Have these strains, in these amounts, been studied in human clinical trials or scientific studies to demonstrate the intended effect?

Why invite billions of bacteria into your body if you don’t expect them to support your gastrointestinal health? When choosing a probiotic, look for clinical and scientific evidence that taking a specific strain at a specific dose will produce the desired health benefit.

As you can see, the notion of a “best” probiotic is far more complicated than it seems. One thing we do know is this: When it comes to probiotics, we’re just beginning to uncover their potential.


1. Almario, C.V. et al, “Burden of Gastrointestinal Symptoms in the United States: Results of a Nationally Representative Survey of Over 71,000 Americans,” Am. J. Gastroenterol 2018 Oct 15
2. Del Piano, M et al, “The use of probiotics in healthy volunteers with evacuation disorders and hard stools, a double-blind, randomized, placebo-controlled study.” Journal of Clinical Gastroenterology 2010 Sep, DOI:10.1097/MCG.0b013e3181ee31c3
3. Takeda, Y et al, “Upregulation of T-bet and tight junction molecules by Bifidobactrium longum improves colonic inflammation of ulcerative colitis.” Inflamm Bowel Dis.15(11):1617-8, 2009 Nov. DOI:10.1002/ibd.20861
4. Byrd, A., et al, “The human skin microbiome.” Nat Rev Microbiol 16, 143–155 (2018).
5. Saito, Y et al, “Effects of intake of Lactobacillus casei subsp. casei 327 on skin conditions: a randomized, double-blind, placebo-controlled, parallel-group study in women,” Bioscience of Microbiota, Food and Health, 2017 Volume 36 Issue 3 Pages 111-120 DOI
6. Drago, F et al, “The role of small intestinal bacterial overgrowth in rosacea: A 3-year follow-up,” JAAD ONLINE| VOLUME 75, ISSUE 3, E113-E115, SEPTEMBER 01, 2016, DOI:
7. Beibei Y, et al. “Effects of regulating intestinal microbiota on anxiety symptoms: A systematic review.” General Psychiatry, 2019; 32: e100056 DOI:
8. Sugahara, H et al, “Differences in folate production by bifidobacteria of different origins” Bioscience of Microbiota, Food and Health, 2015 Volume 34 Issue 4 Pages 87-93 DOI